Just to give you some impression of the OnBoard Audio. It will not be HiFi, but do the job, in case you forgot your headphones 😉 Driven only by AtMega, no OpAmp. Keep it simple.
First of All: The uSDX is not a Product, you can buy. It´s not a Kit, you can buy and build. It´s a true (non commercial) Ham Radio Project, where you need to source your own PCB´s and Parts, if you want to build one. But the result is well worth the effort, as you will end up with a Multi-Band all Mode highly efficient QRP Transceiver !